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In function nfs_permission: 1. the rcu_read_lock and rcu_read_unlock around nfs_do_access is unnecessary because the rcu critical data structure is already protected in subsidiary function nfs_access_get_cached_rcu. No other data structure needs rcu_read_lock in nfs_do_access. 2. call nfs_do_access once is enough, because: 2-1. when mask has MAY_NOT_BLOCK bit The second call to nfs_do_access will not happen. 2-2. when mask has no MAY_NOT_BLOCK bit The second call to nfs_do_access will happen if res == -ECHILD, which means the first nfs_do_access goes out after statement if (!may_block). The second call to nfs_do_access will go through this procedure once again except continue the work after if (!may_block). But above work can be performed by only one call to nfs_do_access without mangling the mask flag. Tested in x86_64 Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.